2014-11-16 21:13:20 +01:00
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// Copyright (C) 2014 The Syncthing Authors.
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2014-09-29 21:43:32 +02:00
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//
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2015-03-07 21:36:35 +01:00
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// This Source Code Form is subject to the terms of the Mozilla Public
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// License, v. 2.0. If a copy of the MPL was not distributed with this file,
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2017-02-09 07:52:18 +01:00
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// You can obtain one at https://mozilla.org/MPL/2.0/.
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2014-06-01 22:50:14 +02:00
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2014-07-31 17:01:11 +02:00
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// Package osutil implements utilities for native OS support.
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2014-05-25 20:49:08 +02:00
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package osutil
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import (
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2014-10-06 09:25:45 +02:00
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"errors"
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2014-12-20 00:12:12 +01:00
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"io"
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2014-05-25 20:49:08 +02:00
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"os"
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2014-08-25 18:14:49 +02:00
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"path/filepath"
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2014-05-25 20:49:08 +02:00
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"runtime"
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2014-10-06 09:25:45 +02:00
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"strings"
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2015-04-23 00:54:31 +02:00
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2017-08-19 16:36:56 +02:00
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"github.com/syncthing/syncthing/lib/fs"
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2015-08-06 11:29:25 +02:00
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"github.com/syncthing/syncthing/lib/sync"
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2014-05-25 20:49:08 +02:00
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)
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2014-09-22 15:48:46 +02:00
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// Try to keep this entire operation atomic-like. We shouldn't be doing this
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// often enough that there is any contention on this lock.
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2015-04-28 22:32:10 +02:00
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var renameLock = sync.NewMutex()
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2014-09-22 15:48:46 +02:00
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2014-12-20 00:12:12 +01:00
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// TryRename renames a file, leaving source file intact in case of failure.
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// Tries hard to succeed on various systems by temporarily tweaking directory
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// permissions and removing the destination file when necessary.
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func TryRename(filesystem fs.Filesystem, from, to string) error {
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2014-09-22 15:48:46 +02:00
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renameLock.Lock()
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defer renameLock.Unlock()
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return withPreparedTarget(filesystem, from, to, func() error {
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return filesystem.Rename(from, to)
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})
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}
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2014-08-25 18:14:49 +02:00
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2017-11-04 08:20:11 +01:00
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// Rename moves a temporary file to its final place.
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// Will make sure to delete the from file if the operation fails, so use only
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// for situations like committing a temp file to its final location.
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2014-12-20 00:12:12 +01:00
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// Tries hard to succeed on various systems by temporarily tweaking directory
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// permissions and removing the destination file when necessary.
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func Rename(filesystem fs.Filesystem, from, to string) error {
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// Don't leave a dangling temp file in case of rename error
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if !(runtime.GOOS == "windows" && strings.EqualFold(from, to)) {
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defer filesystem.Remove(from)
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}
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return TryRename(filesystem, from, to)
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}
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// Copy copies the file content from source to destination.
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// Tries hard to succeed on various systems by temporarily tweaking directory
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// permissions and removing the destination file when necessary.
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func Copy(filesystem fs.Filesystem, from, to string) (err error) {
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return withPreparedTarget(filesystem, from, to, func() error {
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return copyFileContents(filesystem, from, to)
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})
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}
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2014-09-28 01:54:25 +02:00
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// InWritableDir calls fn(path), while making sure that the directory
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// containing `path` is writable for the duration of the call.
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func InWritableDir(fn func(string) error, fs fs.Filesystem, path string) error {
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dir := filepath.Dir(path)
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info, err := fs.Stat(dir)
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if err != nil {
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return err
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}
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if !info.IsDir() {
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return errors.New("Not a directory: " + path)
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}
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if info.Mode()&0200 == 0 {
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2014-09-28 01:54:25 +02:00
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// A non-writeable directory (for this user; we assume that's the
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// relevant part). Temporarily change the mode so we can delete the
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// file or directory inside it.
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err = fs.Chmod(dir, 0755)
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if err == nil {
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defer func() {
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err = fs.Chmod(dir, info.Mode())
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if err != nil {
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// We managed to change the permission bits like a
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// millisecond ago, so it'd be bizarre if we couldn't
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// change it back.
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panic(err)
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}
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}()
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}
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}
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return fn(path)
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}
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2014-10-06 09:25:45 +02:00
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2014-12-20 00:12:12 +01:00
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// Tries hard to succeed on various systems by temporarily tweaking directory
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// permissions and removing the destination file when necessary.
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2017-08-19 16:36:56 +02:00
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func withPreparedTarget(filesystem fs.Filesystem, from, to string, f func() error) error {
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// Make sure the destination directory is writeable
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toDir := filepath.Dir(to)
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if info, err := filesystem.Stat(toDir); err == nil && info.IsDir() && info.Mode()&0200 == 0 {
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filesystem.Chmod(toDir, 0755)
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defer filesystem.Chmod(toDir, info.Mode())
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2014-12-20 00:12:12 +01:00
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}
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// On Windows, make sure the destination file is writeable (or we can't delete it)
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if runtime.GOOS == "windows" {
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filesystem.Chmod(to, 0666)
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if !strings.EqualFold(from, to) {
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err := filesystem.Remove(to)
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if err != nil && !fs.IsNotExist(err) {
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return err
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}
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2014-12-20 00:12:12 +01:00
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}
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}
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return f()
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}
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// copyFileContents copies the contents of the file named src to the file named
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// by dst. The file will be created if it does not already exist. If the
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2017-11-04 08:20:11 +01:00
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// destination file exists, all its contents will be replaced by the contents
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2014-12-20 00:12:12 +01:00
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// of the source file.
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func copyFileContents(filesystem fs.Filesystem, src, dst string) (err error) {
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in, err := filesystem.Open(src)
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2014-12-20 00:12:12 +01:00
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if err != nil {
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return
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}
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defer in.Close()
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out, err := filesystem.Create(dst)
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2014-12-20 00:12:12 +01:00
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if err != nil {
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return
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}
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defer func() {
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cerr := out.Close()
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if err == nil {
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err = cerr
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}
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}()
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2016-11-22 08:59:54 +01:00
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_, err = io.Copy(out, in)
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2014-12-20 00:12:12 +01:00
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return
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}
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2015-05-05 21:19:59 +02:00
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var execExts map[string]bool
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func init() {
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// PATHEXT contains a list of executable file extensions, on Windows
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pathext := filepath.SplitList(os.Getenv("PATHEXT"))
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// We want the extensions in execExts to be lower case
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execExts = make(map[string]bool, len(pathext))
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for _, ext := range pathext {
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execExts[strings.ToLower(ext)] = true
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}
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}
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// IsWindowsExecutable returns true if the given path has an extension that is
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// in the list of executable extensions.
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func IsWindowsExecutable(path string) bool {
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return execExts[strings.ToLower(filepath.Ext(path))]
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}
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2018-02-25 09:27:54 +01:00
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func IsDeleted(ffs fs.Filesystem, name string) bool {
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if _, err := ffs.Lstat(name); fs.IsNotExist(err) {
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return true
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}
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switch TraversesSymlink(ffs, filepath.Dir(name)).(type) {
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case *NotADirectoryError, *TraversesSymlinkError:
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return true
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}
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return false
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}
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